Abstract:
An extreme geomagnetic storm has the potential to affect various technologies and activities
in space and on the ground, e.g., power grids, oil and gas industries, communications,
ground transportation, satellite infrastructure, global navigation satellite systems, aviation,
etc. Therefore, it is considered a major source of risk by various governmental agencies and
corporations at the international level. All notable space weather events (superstorms) are
caused by interplanetary coronal mass ejections (ICMEs). But not every ICME leads to an
extreme storm. Moreover, how does an extreme storm form? Or which explicit characteristic
of ICME actually is responsible for inducing a superstorm? Here, we re-investigate
the ICME characteristics that contribute to the most intense storm of the current century
that occurred on 20 November 2003. Interestingly, the studied ICME magnetic cloud shows
characteristics of extremely flattened (pancaked) structure i.e. quasi-planar magnetic structure
(PMS). The pancaked ICME shows less adiabatic expansion than usual in the compressed
direction, which leads to strong magnetic field strength, high plasma density, high
solar wind speed, high dynamic pressure, and a high eastward interplanetary electric field.
Here, we propose that the ICME that transformed into a quasi-PMS has the aforementioned
enhanced features with strong southward magnetic field component that contributes to efficiently
transferring plasma and energy into the Earth’s magnetosphere to cause the observed
superstorm.
